Packaging pad



March 12; 1968 F. G. LOGAN u, ET AL 3, 2,

PACKAGING PAD 2 Sheets-Sheet 1 Filed Nov. 25, 1966 IN VENTOR. FPRNKGLOGHN 11 B Y HARRY WILLIAM THHTCHER ATTORNEY March 12, 1968 F. G. LOGAN II, ET AL 3,372,795

PACKAGING PAD 2 SheetsSheet 2 Filed Nov. 23, 1966 mv 9v H N I N Iv W A V 9v. 1

a kw Qf m R E C m m m M w E N M T HAM A VGU Nmm [GM m mm A F H Y B a United States Patent 3,372,795 PACKAGING PAD Frank G. Logan II, Framingham, and Harry William Thatcher, Mendon, Mass, assignors to Worcester Moulded Plastics Company, Worcester, Mass. Filed Nov. 23, 1966, Ser. No. 596,610 9 Claims. (Ci. 206-46) ABSTRACT OF THE DISCLOSURE This invention pertains'to cushioning means for protecting packaged products from damage by'irnpact, and more particularly to molded expandable plastic pads within or between whicha fragile article may be enclosed or held in suspension.

A large portion of the overall cost of certain manufactured items derives from the necessity of protecting them from damage by shock and collision during shipping and storing'operations. Articles which are limited in the degree of shock they can safely withstand would include electronic equipment, delicate instruments, cameras and glassware. Theseitems each have aknown shock-resistance limit as established by testing and experience. Many critical cushioning methods have been used to prevent that limit from being exceeded for each particular type of article. A well known device for critical packaging includes corrugated die cuts shaped by cutting and folding to separate the article from the outer container in a restrained position. Corrugated paper board has quite limited capacity for elastic deflection and when overstrained, will buckle and collapse. This may leave the article loose within the container and subject to damage through impact or collision upon any subsequent drop.

Molded pads of expandable polystyrene offer increased elasticity compared to corrugated and, provided the projected areas of the molded pads are properly chosen to compensate for the known weight and extent of drop, will sustain multiple falls. Many of the articles to be protected require more cushioning than can be obtained economically by straight elastic deflection designs. To reduce the bulk and obtain higher deflection with molded pads, crush ribs have been provided with satisfactory results in the event of a single drop. It has been found that damage would result with subsequent drops after crushing of the ribs had taken place.

The packaging pad of the instant invention employs the open bridge-truss principle to combine the major advantages of high elastic deflection with non-permanent deformation. In bridge design the penalty for using open trusses as against solid construction has been increased deflection. This penalty has been turned to advantage for use in critical packaging. The integral formation of the truss and plate members prevents local buckling of the trusses and will absorb initial impact stresses through shear force absorption before taking any high loading as a truss or absorbing decelerative forces by high elastic deflection. The integral formation also permits relatively thin and uniform wall sections which result in savings in the material used as well as labor costs from rapid molding procedures.

The open truss and plate structure, while greatly re- 3,372,795 Patented Mar. 12, 1968 duced in weight, will give maximum columnar strength for stacking purposes. Filled containers may be stored ceilinghigh without the possibility of crushing.

It is a general object of the invention to provide a cushioning pad for critical packaging conditions to protect against the second-impact forces resulting from multiple drops.

It is another object of the invention to provide a packaging pad which shall combine the properties of highelastic deflection with non-permanent deformation.

It is a further object of the invention to provide a molded packaging pad having unitary bridge-truss formation.

It is a further object to provide a packaging pad of minmum weight having high shock-absorbing qualities for protection against falls from any angle.

It is a still further object of the invention to provide a packaging pad formation which shall be economical in both molding time required and the use of materials.

These and other objects of the invention will become apparent as further details are described in detail by reference to a specific embodiment thereof as shown in the accompanying figures of drawing, wherein:

FIG. 1 is a plan view of the packaging pad showing the truss construction surrounding the receiving enclosure; and

FIGS. 2-3 and 4 are vertical sections taken on lines- 2 2, 33- and 4-4, respectively, in FIG. 1.

Now referring to the drawings, the pad may be molded as a unit having an upright outlying perimeter wall 20 defining a standard built-up height as at 21 (FIG. 2) throughout its full extent. The pad housing is framed on all sides to the built-up height 21 by upright members 22, 23, 24, 25, 26 and 27 each generally parallel to its adjacent upright perimeter wall. The upright members are" interconnected with the wall 2%" in bridge-truss formation by diagonal uprights or ribs 28 to form A cavities 29 at the cor ers, V cavities 30 along the sides, and diamond-shaped cavities 31 adjacent to where the ribs are caused to intersectiFlG. 1).

Upright members 22, 23, 24, 32 and .33 circumscribe a receiving enclosure (FIG. 1), defining a first supporting height 34 (FIGS. 2 and 4), and surround an inner upright wall 35. The wall 35 forms an opening 36 completely through the housing and in this open area any break-out inserts 37 may be molded simultaneously with the pad if needed. Diagonal uprights 28 extend between the upright wall 35' and each adjacent parallel upright member and also form cavities 3t and 31 therebetween.

A further portion of the receiving enclosure is generally bounded by upright members 25-, 26, 27, 32, 3'3 and 35 and rises to a lower supporting height 38 (FIGS. 2 and 3) for matching the contours of a portion of a particular product. An additional enclosure is contained between upright walls 39, 4t} and a small portion of wall 35 and also rises to the lower supporting height 38'. Diagonal uprights 28 extend across and reenforce these two portions of the enclosure in a bridge-truss form as before. The truss areas have a solid backing 41 which may cover the bottom face of the housing partially or completely with the exception of the opening 36 (FIGS. 2 and 3). Truncated corners 42 distribute impact forces Without damage by permitting the exterior container to absorb the initial impact forces.

The frame truss area at the built-up height 21 surrounds r the receiving enclosures of all heights in a manner to protect a fragile product either within two mating pads or by being suspended between fixedly separated pads. End-wise forces perpendicular to the backing 41 are absorbed by the diagonal uprights 2S and other upright members which have trapezoidal cross sections as at 43 and 44 (FIGS. 3 and 4). These provide progressive decelerative compression cushioning.

A portion 45 of the perimeter wall 20 is molded with a zero-draft condition so as to be at a right angle with the backing 41 for providing columnar support for the package. This will give rigid support during stacking conditions without translating the stress to the product inside.

The instant invention provides a packaging pad which, by using a bridge-truss principle, eliminates the usual second-impact damage from multiple drops. The truss principle provides higher elastic deflection without permanent deformation than other critical packing means. The truss principle allows a reduction in material used and in molding time with a resulting reduction in weight. Thermoplastic beads of polystyrene have been found effective for the invention because of high density and fast expansion properties. A suitable material of expandable polystyrene is sold under the name Dylite a trademark of Sinclair- Koppers Company, Pittsburgh, Pa.

It will be readily seen that the enclosures within the built-up frame areas are variable and may be easily adapted to suit the contour requirements of a plurality of various shaped products.

While one embodiment of the invention has been disclosed, it is to be understood that the inventive concept may be carried out in a number of ways. This invention is, therefore, not to be limited to the precise details described, but is intended to embrace all variations and modifications thereof falling within the spirit of the invention and the scope of the claims.

We claim:

1. A packaging pad for cushioning fragile products from the damaging forces of impact which comprises (a) a molded housing of thermoplastic material having an outlying perimeter wall and a generally centrally disposed receiving enclosure,

(b) said receiving enclosure being adapted to encompass at least a portion of the contours of a fragile product,

(c) a multiplicity of interconnected and angularly disposed ribs intermediate said perimeter wall and receiving enclosure,

(d) said ribs forming truss areas for completely framing said receiving enclosure, and

(e) a solid backing extending over at least part of one face of said truss areas.

2. A packaging pad according to claim 1 wherein each one of said truss areas includes two upright parallel members being interconnected by a plurality of diagonal members.

3. A packaging pad according to claim 2 wherein said diagonal members combine in forming V shaped cavities between said parallel members.

4. A packaging pad according to claim 2 wherein at least part of said diagonal members intersect forming diamond-shaped cavities therebetween.

5. A packaging pad according to claim 2 wherein said diagonal members intersect at the corners of said pad forming A shaped cavities.

6. A packaging pad according to claim 2 wherein at least a portion of said perimeter wall is normal to said solid backing.

7. A packaging pad according to claim 6 wherein said upright parallel members and said diagonal members define trapezoidal cross sections.

8. A packaging pad according to claim 7 having said housing and said backing formed integrally of expanded polystyrene foam.

9. A packaging pad according to claim 8 wherein said diagonal members and said upright parallel members combine in forming A, V, and diamond-shaped cavities therebetween.

References Cited UNITED STATES PATENTS 2,758,772 8/ 1956 Williams 206-46 3,114,457 12/1963 Knapp et al. 206-72 3,181,698 5/1965 Knapp et al. 206--72 3,191,791 6/ 1965 Jackson 206-46 3,243,037 3/1966 Luertzing 206-46 3,251,460 5/ 1966 Edmonds 206-46 3,266,705 8/1966 Wood 206--46 MARTHA L. RICE, Primary Examiner.

LOUIS G. MANC-ENE, Examiner. 

